Proteins Provide Clues to Nanomaterial Toxicity
Adsorbed albumin influences biological activity of two kinds of nanomaterials
Results: Scientists are looking for ways to predict adverse effects of nanomaterials on human health and the environment. Nano-size particles are characterized by diverse physicochemical properties and may reach sites within cells and tissues not previously or routinely compromised. This challenging combination makes it hard to predict the toxic potential of nanomaterials.
Researchers from Pacific Northwest National Laboratory, the University of California-Davis and the University of Florida have found that proteins adsorbed onto nanomaterials play an important role in directing nanomaterial disposition and toxicity. This provides important clues about sites of potential toxicological interest. Their research was published in the November 2007 issue of Toxicological Sciences.
Why it matters: Nanomaterials are typically defined as engineered structures with at least one dimension of 100 nm or less. They can have unique properties resulting from the combination of their small size, chemical composition, surface structure, solubility, shape and aggregation.
Recent years have witnessed a dramatic increase in research at the nanometer scale. New opportunities have become evident in many industries—from consumer products and drug delivery to solar cells and aerospace materials. However, materials that are inert in bulk form may be toxic in nano-sized form, which argues that nanomaterials be systematically evaluated for their toxic potential.
Methods: The researchers investigated the toxicity of two classes of nanomaterials, single-walled carbon nanotubes (or SWCNTs) and spherical structures (10-nm amorphous silica) with and without surfactant coating to prevent protein adsorption. They observed that albumin was the major protein adsorbed to carbon nanotubes and was linked to uptake of nanomaterial by cultured cells. This response was associated with reduced expression of cyclooxygenase-2 (COX-2), an enzyme that can reduce inflammation. Surfactant-coated nanotubes did not exhibit anti-inflammatory properties, and the loss of such properties was correlated to a lack of albumin binding to surfactant-coated nanotubes.
What's next: The data suggest that developing a comprehensive understanding of proteins adsorbed to the surface of nanomaterials could help in understanding how these materials are processed in complex biological systems. This knowledge is expected to improve the understanding of nanomaterial toxicity.
Acknowledgments: This research was funded by PNNL's Environmental Biomarkers Initiative and Summer Research Institute in Interfacial and Condensed Phase Chemical Physics, the National Science Foundation and the Department of Veteran's Affairs. The research team included Debamitra Dutta, SK Sundaram, Justin Teeguarden, Brian Riley, Leo Fifield, Jon Jacobs, Shane Addleman, and Tom Weber, all PNNL; George Kaysen, UC Davis; and Brij Moudgil, University of Florida.
Reference: Dutta D, SK Sundaram, JG Teeguarden, BJ Riley, LS Fifield, JM Jacobs, SR Addleman, GA Kaysen, BM Moudgil, and TJ Weber. 2007. "Adsorbed proteins influence the biological activity and molecular targeting of nanomaterials." Toxicological Sciences 100(1):303-315.